[gls2ro]

For me the service they offer is exchanging money for time:

Going into a shop is more than the walk or drive. It is looking for a product, waiting in line if there is a line to pay, start the car, drive back, look for a parking spot. I would say that shopping 2-3 products from a 10-15 minute store, could cost at least 30 to 60 minutes time if going on foot and if driving probably more than one hour.

I count this time from the moment I decide I have the need until I am back home.

If a grocery delivery service can buy in the same time from the same store for at least two people I would say they also decrease fuel consumption. This could be a long shot.